Winter flooding, warm ocean likely affected Southeast humpies

Pink salmon, plus an occasional silver and red, congregate in a pool above the weir before spawning. Biologists say the males will put on displays and fight with other males as part of the competition for mating females which have already started a nest. (Photo by Matt Miller/KTOO)

This year’s pink salmon or humpy runs in Southeast Alaska weren’t horrible, but they weren’t great either. Fish returns weren’t consistent across the Panhandle.

“Northern Southeast turned out good, above average. But southern Southeast just tanked,” said Joe Orsi, a research fisheries biologist at NOAA’s Ted Stevens Marine Research Institute in Auke Bay.

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Orsi speculates that warm sea surface temperatures may be responsible for this year’s high survival rates or larger fish size. But those results don’t appear to be universal for all pink runs in Southeast Alaska.

“Basically it’s about a million or so fish higher than the 10-year average in northern Southeast. But southern Southeast Alaska, it’s been like 10 million fish below the 10-year average. So, there appears to be a split in the production and survival of pink salmon about in the middle of Southeast Alaska.”

Auke Creek fish weir
NOAA’s Scott Vulstek, left, and UAS’s Joshua Russell, center, and Donovan Bell count salmon and take genetic samples at the Auke Creek weir. Native pinks, reds and silvers are put back into the creek above the weir so they can continue to spawn. Wayward hatchery kings and chums are separated out and disposed below the weir. Coded wire tags implanted earlier into the nose of the kings will provide detailed information about their hatchery origin. The kings and chums are then put into the white tube that carries them back down below the weir. Their remains will add to cycle of life at the mouth of the creek. (Photo by Matt Miller/KTOO)

But why? For now, Orsi said they can only speculate on the reasons.

“I know they had a lot of flooding events last winter down there. That’s a possibility,” Orsi said. “There could’ve been a mismatch of the fish entering the marine environment and the timing of the zooplankton down there. There could’ve been an assortment of predators or competitors that came up with the warm Blob that may have impacted the juvenile salmon. There’s just a lot of unknowns.”

The Blob is the nickname given to the ongoing warm water anomaly in the North Pacific, and it is different than El Niño that is now developing in the equatorial Pacific.

Auke Creek sockeye
University of Alaska Southeast intern Joshua Russell holds up a squirming adult red or sockeye salmon before pitching it back into the water so that it can continue up the creek to spawn. (Photo by Matt Miller/KTOO)

Pink salmon returning to Southeast Alaska this year were the children of 2013’s big return that formed the basis for that season’s record harvest of 89 million fish.

Orsi earlier predicted that 54 million pinks would be harvested this season. Going off of his numbers, the Alaska Department of Fish and Game forecasted a range of 37 million to 58 million fish that would be taken by all gear types.

But this season’s harvest barely approached the low end of that range. Orsi conceded that he was way off.

“Last year, we predicted a fairly good pink salmon return to Southeast Alaska,” Orsi admitted. “I kind of have to face the music. We didn’t get that strong return this year.”

According to latest figures released by the Alaska Department of Fish and Game, 34.1 million pinks were harvested in Southeast Alaska during 2015 with fishermen at the dock getting paid $26.2 million. Pinks comprised a significant chunk of the region’s all-species harvest of 46.2 million fish that were valued at $89.3 million. Pinks were a little heavier this season, but about 3 million fewer fish were caught and the price paid to fishermen was about 25 percent less than last year.

John Joyce
NOAA research fisheries biologist John Joyce explains their operation at the Auke Creek Hatchery and Weir, and why 35 years of continuously collecting salmon data is so important for fisheries managment. (Photo by Matt Miller/KTOO)

Outside of Southeast Alaska, Prince William Sound and Kodiak Island also reported very strong pink catches. It’s also unclear whether The Blob or a El Niño had any impact on those runs.

Auke Creek is just one example of how some streams in northern Southeast had better returns than other streams further south. The Auke Creek Hatchery and Weir is a small, federally-operated facility tucked away in the woods in the 1,500 feet between Auke Lake and Auke Bay.

John Joyce, also a research fisheries biologist and one of Orsi’s colleagues at the NOAA institute, spends a lot of his time at the weir. He uses words like “phenomenal” and “incredible” to describe 24,352 big pinks that returned to Auke Creek this summer. That’s over a 51 percent survival rate for the 47,000 juvenile salmon that passed out of Auke Creek and into the ocean last year. Normal survival rates for returning salmon range from 0.1 to 10 percent.

Joyce said returning fish were big, too.

“Pinks are the largest I’ve seen in the last 10 years,” he said. “As big as an average size chum.”

Joyce said local geography and the relatively low drainage area are big factors in the health of the system.

“Flow is very important,” Joyce said.

Auke Creek Hatchery and Weir
Biologists at the Auke Creek Hatchery and Weir have been counting fish for the last 35 years. (Photo by Matt Miller/KTOO)

A low snowpack in the Auke Lake drainage melted early in March and April this year. That was followed by a very dry May and then heavy rain by July.

“So, all of that affects not only the flow in the creek, but also the temperature,” Joyce says.

“Temperature and flow are really important factors for fish that migrate, for juveniles and adults.”

The Auke Creek facility is unique because biologists have data on stream flow and water temperatures that correspond with 35 years of continuously counting salmon that swim in and out of the stream.

Joyce said they noticed silver or coho returns have been compressed into largely a two-week period while pink runs have trended two weeks earlier over the last three decades.

“It’s substantial. And it has ecological implications, too, because these juveniles have adapted to certain timing to enter the ocean,” Joyce said. “That adaption to timing could be differently influenced in fresh water than salt water. So, you could potentially have a mismatch where they’re going faster in fresh water but the ocean is not ready for them.”

Coho genetic sampling
University of Alaska Southeast intern Donovan Bell retrieves a genetic sample from a coho being held by Joshua Russell. (Photo by Matt Miller/KTOO)

Joyce said their research into migratory behavior and ocean survival has implications for resource management.

“If you have salmon that used to run over a month and you could access them and now they’re running over two weeks, it affects your ability to harvest, it affects predators’ ability to kill. So, it does have ecological impacts in terms of the systems, too,” Joyce said.

As an example of some of the research at the weir, Joyce said they collect genetic samples from sockeye and coho salmon that reveal clues about their origin and ocean growth.

Joyce said they’re collaborating with the University of Alaska of Southeast, which is using their 35 year data sets in their research to determine how climate change is influencing migratory behavior, marine survival and productivity.

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